The best and cheapest technologies for server/ services/ hostings

my question is maybe stupid, but I belive that lots of newbies as me would like to know it.

I would like to create some web application nor desktop application, lets say some multiplayer game for this case. It means I need some server. My idea is to have some desktop nor web application as a client which will call some services/ methods on the server, change there something and get some responses.

My question is what kind of this "server or whatever" can I use? I have some experiences with making webpages, so I know I can have some webhostings, but this webhostings just store the data for webpages and I can imagine that I will create there something in php as a "server", but I feel it is not a good solution. I also know for example firebase. It is super cool for data exchange for my purposes, but not for a server logic (ex. check if your hero can go on this field from his actual position...). So I need something like betweet firebase and the client.

I'm not looking for exact tutorial, I just want to ask you what options I have/ what technlogoies I can use/ what should I look for. Can you write me some options and their pros and cons (usage, price, difficulty, speed, language...) what can I use for desktop client, web client, desktop and also web client together? I also prefer .NET and C#, but it is not requied.

Thank you.